Chapter 9

And it was on the eighth day: of the investitures. It was the first of the month of Nissan, the very day on which the Mishkan was erected. And [this day] took ten “crowns” [of distinction], which are enumerated in Seder Olam 7. — [Torath Kohanim 9:1]

[called…] the elders of Israel: to inform them that it was by the express command of God that Aaron was entering into the Kehunah Gedolah , so that they should not say that he entered of his own accord.

Take for yourself a bull-calf: [This was] to inform [Aaron] that the Holy One, Blessed is He, had granted him atonement through this calf for the incident involving the [golden] calf, which he had made. — [see Tanchuma 10]

קח לך עגל: להודיע שמכפר לו הקב"ה ע"י עגל זה על מעשה העגל שעשה:

3And to the children of Israel, you shall speak, saying, 'Take a he goat as a sin offering; and a calf and a lamb, [both] in their first year and [both] unblemished, as a burnt offering,

7And Moses said to Aaron, "Approach the altar and perform your sin offering and your burnt offering, atoning for yourself and for the people, and perform the people's sacrifice, atoning for them, as the Lord has commanded.

Approach the altar: [Moses had to order Aaron to do so,] because Aaron was bashful and afraid to approach [the altar]. So Moses said to him: “Why are you ashamed? For this [function] you have been chosen!” - [Torath Kohanim 9:7]

the people’s offering: The he-goat, the calf, and the lamb. Wherever the [unqualified] term עֵגֶל (calf) is stated [in Scripture], it denotes one in the first year. This [rule] is derived from this passage. [The term פַּר denotes one in the third year, עֵגֶל בֶּןבָּקָר one in the second year, and עֵגֶל one in the first year.]- [Torath Kohanim 4:208]

the flesh and the hide: We do not find [in Scripture] an outside sin-offering [i.e., one whose blood is sprinkled on the outside altar] to be burned, with the exceptions of this [instance] and [the sin-offerings] of the investitures. And all these [exceptions] were [burnt] at the express command [of God].